According to the generally known state of the art, shells for the production of the aircraft fuselage can be manufactured in a negative adhesive bonding unit, which is referred to as a laminating adhesive bonding unit (LABU). Fibre material and resin are applied in several layers into said negative adhesive bonding unit and hardened. Also the stringers are integrated on top of or within this layered structure. The LABU determines the desired external shape of the construction. After demoulding, a chip-producing subsequent work process is often performed before the shells modeled such can be mounted.
DE 103 31 358 A1 discloses a particular apparatus for the serial production of a fuselage shell for an aircraft consisting of a fibre composite. On a plane forming jig, a grid pattern of several support walls of different lengths is arranged such that their ends form, approximately, a semi-circle. The support walls are arranged towards the jig in angles, which are defined by the semi-circle. At the distal ends of the support walls forming the semi-circle, modular sectional profile members are arranged, which cover the gaps between the support walls and the outer surfaces and which correspond in a negative sense, as a mounting surface, to the inner shape of the integral structural component to be fabricated.
The grid pattern of the support walls as well as the division of the modular profile members is embodied such that each gap between them is arranged below the target position of each stringer. Thus the gap for the positioning of the stringer is used relative to the fuselage shell to be fabricated. A LABU matching the above described mounting device is, after the establishment of the complete structure of the shell and of the auxiliary materials is applied, exactly matching, above the mounting surface, and the encircling sealant that was applied onto vacuum foil beforehand is pre-solidified such that a vacuum-tight sealing is obtained between the vacuum skin and the LABU. Subsequently, the construction is evacuated on the side of LABU.
The fuselage shell, which is equipped with stringers, is produced by means of the apparatus described above such that, firstly, a loose film is applied to the outer surfaces of the modular profile members. Subsequently, the hollow space that is formed by the gaps between the profile members is evacuated such that the atmospheric pressure presses the foil exactly into the profile grooves and indentions. Then, the auxiliary materials can be laid on the vacuum-molded foil. In the following, stringers embedded into elongated form parts are set into the profile grooves covered by the vacuum foil. In doing so, the elongated formed parts form a kind of adapter to adjust the form between the geometry of the gap in the mounting surface and the geometry of the stringer to be processed. Depending on the fabrication process, all shell layers made of fibre composites are applied individually or as a package onto the outer surface of the modular profile members of the mounting device and the stringers covered by vacuum foil. Subsequently, a sealant is applied onto the vacuum foil in an optimized amount. By a precise bringing together of the structure onto the mounting device prepared such with the corresponding LABU, the sealant around the perimeter is solidified such that a vacuum-tight sealing between said vacuum foil and the LABU is obtained. To perform the transfer of the complete structure from the mounting device into the LABU, the side of the mounting device is aerated and, subsequently, vacuumed on the side of the LABU. Thus the complete structure is pressed against the LABU with atmospheric pressure. Eventually, the mounting device and the LABU are brought apart and the LABU is turned such that it can be subjected to a final hardening process.
By means of said continuous formed parts for the positioning of the T stringers relative to the mounting surface, a precise production of the reinforced fuselage shell can be obtained, however, the elongated formed parts are not easy to handle and difficult to produce. In addition, before every application release agents need to be applied on the elongated formed parts, and they must be cleaned as well, which requires a lot of work.
The elongated formed parts are not adjustable relative to the gap, which forms a matching mounting groove, such that narrow tolerances need to be observed during the production of the elongated formed parts. This, additionally, increases the production effort. In addition, while co-acting with the LABU, it is not possible to actively guide the stringers during the transfer process. A minimum distance is required to feed the mounting device into the corresponding LABU, which requires a movement of the mounting device in the course of the transfer process from the mounting device to the LABU—more precisely, a directed movement towards a target. In most cases, the elongated formed parts for the T stringer used up to date, however, show a different geometry for each stringer by intended local swellings at the shell layers such that a large number of said form parts must be provided in order to process the different kinds of stringers.
Often, production methods for fuselage shells comprise what is commonly called hard stringers. In these cases, stringers consisting of metal or of already hardened composite materials are applied which, therefore, cannot be processed in a non-hardened state.